Fix a display glitch when an OTA is initiated while an app (other than Clock) was open and while the device was in sleep mode.

Author: JF002

src/displayapp/screens/FirmwareUpdate.cpp

@@ -9,6 +9,12 @@ using namespace Pinetime::Applications::Screens;
 FirmwareUpdate::FirmwareUpdate(Pinetime::Applications::DisplayApp *app, Pinetime::Controllers::Ble& bleController) :
       Screen(app), bleController{bleController} {
 
+  lv_obj_t * backgroundLabel = lv_label_create(lv_scr_act(), nullptr);
+  lv_label_set_long_mode(backgroundLabel, LV_LABEL_LONG_CROP);
+  lv_obj_set_size(backgroundLabel, 240, 240);
+  lv_obj_set_pos(backgroundLabel, 0, 0);
+  lv_label_set_text_static(backgroundLabel, "");
+
   titleLabel = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(titleLabel, "Firmware update");
   lv_obj_set_auto_realign(titleLabel, true);